Walking guided tours of downtown Butler are being held. A walking tour of McKean Street will be offered from 1:30 to 3 p.m. Sept. 16,with a starting location to be determined. Cost is $10 for adults and $5 for children age 12 and younger. To reserve a spot, call 724-256-5769 or e-mail info@butlerdowntown.org.

Harmony Museum, Mercer Street, Harmony, offers its final German dinner of the year Sept. 15 in Stewart Hall, 218 Mercer St. Cost is $17, with proceeds benefiting museum operations. For prepaid reservations, required for sittings at 4:30 or 6:30 p.m., call 724-452-7341.

The Model Engine Collectors Association will have its annual convention EXPO XIII Saturday and Sunday at the Four Points Sheraton Pittsburgh North. There will be engine displays beginning at 10 a.m. Saturday and running of antique and unusual engines in the afternoon, including pre-war model airplane engines. There will be a large engine and engine-related items swap meet from 8 a.m. to noon Sunday. For fees, contact Bill Mohrbacher, MECA president, by calling 724-846-4658 or sending e-mail to gwmfox35@comcast.net.

Phipps Conservatory and Botanical Gardens at One Schenley Park presents the summer flower show “Fountains of Youth” through Sept. 30. Phipps is open daily from 9:30 a.m. to 5 p.m. and until 10 p.m. Fridays. Admission is $12 for adults; $11 for senior citizens and students with ID; $9 for children ages 2 to 18; and free for children younger than 2. Call 412-622-6914 or visit phipps.conservatory.org.Carnegie Science Center, North Side, hosts radio personality Abby Krizner and guitarist Jason Sichi from 2 to 3 p.m. Saturday as part of the science center’s acoustic performance series running during the traveling exhibit: “Guitar: The Instrument That Rocked The World.” The performance is free with regular admission, which is $17.95 for adults and $11.95 for children ages 3 to 12. Most activities are included in the admission price, but some, like Omnimax films, cost extra. The center is open from 10 a.m. to 7 p.m. Saturdays and 10 a.m. to 5 p.m. Sundays through Fridays. Call 412-237-3400.National Aviary, 700 Arch St., has a burrowing owl exhibit, as well as “Parrots of the Caribbean” and the rooftop Sky Deck theater featuring birds of prey in free-flight demonstrations. The aviary is open daily from 10 a.m. to 5 p.m. Admission is $13 for adults, $12 for senior citizens, $11 for children ages 2 to 18, and free for children younger than 2. Call 412-323-7235 or visit www.aviary.org.ToonSeum, Pittsburgh’s Museum of Cartoon Art at 945 Liberty Ave., presents “Pearls Before Swine: The Art of Stephan Pastis” through Sept. 30. Admission is $4 for adults and free for children 12 and younger. Hours are 10 a.m. to 3 p.m. Wednesdays and Thursdays, 10 a.m. to 5 p.m. Fridays and Saturdays and 11 a.m. to 4 p.m. Sundays. Call 412-232-0199.Children’s Museum, 10 Children’s Way, Allegheny Square, opens “Tough Art” on Sept. 14. Hours are 10 a.m. to 5 p.m. daily. Admission is $13 for adults, $12 for children ages 2 to 18 and senior citizens, and free for children younger than 2. Call 412-322-5058 or visit www.pittsburghkids.org.